Pulse width modulated binary rebalance rate capture loop control for two-degree-of-freedom dry tuned gyro

Abstract

A dry tuned two axis gyro having a pulse-rebalanced rate capture loop control. This configuration eliminates the need for an analogue-to-digital converter since the gyro is torquered at a pulse rate using a constant current source. Another feature of the control loop is a cross-channel shaping network which exchanges an electronically damped error from one axis to the other axis. By means of a summing network which combines the error signals from the main channel and the cross channel with a source of time varying ramp voltage, an alternately negative to positive signal is applied to the gyro torquer.

What is claimed is: 
     
       1. A two axis gyro comprising: means for sensing gyro rotor position along a first and second axis, said sensing means also providing proportional error signals along said first and second axes when said rotor deviates from null position,   a source of ramp voltage signals,   means for electronically damping said error signals by summing said error signals with said source of ramp voltage signals whereby a pulse width modulated signal is produced whose fundamental frequency is the frequency of the forced limit cycle of said gyro, and   means responsive to said electronically damped signal for alternately applying a positive and a negative torquing constant current to the first and second axes of said gyro in order to reduce said error signals.   
     
     
       2. The two axis gyro of claim 1 comprising: means for exchanging the error signals between said first and second gyro axes.   
     
     
       3. A pulse rebalanced rate capture loop control for a two axis dry tuned gyro comprising: a first axis pickoff means,   a second axis pickoff means said first and second pickoff means sensing gyro rotor position and producing an electrical error signal,   means for amplifying said error signal from said pickoff,   a demodulator for processing the output signal from said amplifier,   a filter circuit for filtering the output signal of said demodulator,   a main channel shaping network for shaping the output signal of said filter circuit,   a cross channel damping network for exchanging the error signals from both of said gyro axes,   a source of ramp voltage signals,   a summing network for processing the outputs signals of said main channel network, said cross channel network and said source of ramp voltage signals,   logic means responsive to said summing network for alternately applying a positive or negative torquing current to said gyro, and   a source of constant current responsive to said logic means for applying a pulse modulated torquer current to said gyro.   
     
     
       4. A pulse rebalanced rate capture loop control for a two axes dry tuned gyro comprising: pickoff means for sensing gyro rotor position and for providing error signals along the axes of said gyro,   an ac amplifier for amplifying said error signal from said pickoff means,   a demodulator for processing the output from said amplifier,   a filter circuit for filtering the output signal of said demodulator,   a main channel shaping network for shaping the output signal of said filter circuit,   a cross channel damping network for exchanging the error signals between both gyro axes,   a source of ramp voltage signals,   a summing network for processing the output signals of the main channel, the cross channel and the ramp voltage,   logic means responsive to said summing network for alternately applying a positive or a negative torquing current to said gyro, and   constant current sources responsive to said logic means for applying a pulse modulated source of torquer current.